1. Technical Field
The present invention relates to a semiconductor package and a manufacturing method thereof, and more specifically, to a countermeasure against exfoliation of a filter that is disposed in the semiconductor package, and even more specifically, to a countermeasure against exfoliation of a filter that is disposed on a cap substrate in packaging on a wafer level of a semiconductor device.
2. Related Art
For recent mobile phones, mobile information terminals, and mobile electronic devices such as digital cameras, their portability and weight saving are major market needs. For that reason, further reductions in the size and thickness of chips such as semiconductor integrated circuits that are mounted therein are essential. In addition, a stable manufacturing process is called for.
In optical semiconductor devices such as charge-coupled devices (CCDs) and complementary metal-oxide-semiconductors (CMOSs) that are mounted in these mobile electronic devices, optical filters, such as an infrared cut-off filter, are used. When applying these optical filters to a wafer level package of an optical semiconductor, package processing may be performed that consists of forming an optical filter on a glass substrate.
As procedures of forming a filter on a conventional glass substrate, there is a method that forms a filter on a glass substrate after the completion of package processing, and there is a method that first forms a filter on a glass substrate and then performs package processing. In the case of forming a filter in the interior of a package in order to protect the filter, the latter method is adopted. Also, although the former involves separately forming a filter in each package, the latter has the advantage of being able to form a plurality of filters at the wafer level all at once.
FIG. 13 is a cross-sectional view of a manufacturing process for a conventional semiconductor package in which a filter is formed in a package. In the manufacturing process for this semiconductor package 40, as shown in (a) of FIG. 13, the filter 46 is disposed on a surface 44a of a cap substrate 44. Next, the filter 46 and a semiconductor substrate 42 are joined via a spacer 45. Next, as shown in (b) of FIG. 13, dicing of the semiconductor wafer is carried out at the location shown by the dashed line L. Due to chipping that occurs during this dicing process, there is the possibility of exfoliation of this filter 46 occurring as shown in (d) of FIG. 13. This exfoliation 60 of the filter 46 is magnified in a reliability test and the like, and at times it has caused the semiconductor package 40 to malfunction. Also, since the spacer 45 is directly adhered to the filter 46, when the adhesion between of the filter 46 and the cap substrate 44 is weak, there is the possibility of the filter 46 exfoliating under the stress arising from expansion and contraction of the spacer 45.